From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4D53CCA479 for ; Mon, 11 Jul 2022 02:20:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229501AbiGKCU5 (ORCPT ); Sun, 10 Jul 2022 22:20:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229607AbiGKCUy (ORCPT ); Sun, 10 Jul 2022 22:20:54 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4D757183AA for ; Sun, 10 Jul 2022 19:20:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657506049; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yiT1eLlqkfPZrENplLR+NiQCkEFdX9LuuEGtFfnHdws=; b=dRm1QKePKC+4vtU76TvchqeVmMAFd5Zr9zdXNrUvW4qxTZJiM637FZLFVPjggFvd4ghCZS diQlLIQ03J8fekUpAYfEMrw40mzPl2shoYLhDL4PpcUCeXUdk+zsZT5BK3fvvpz4Qcw21o +Eh9F62aGbf53Pbb/RtFMBl7jPvE8r4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-594-kPEFzlcjNmGi1amj0h_NnA-1; Sun, 10 Jul 2022 22:20:44 -0400 X-MC-Unique: kPEFzlcjNmGi1amj0h_NnA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7BF58185A7A4; Mon, 11 Jul 2022 02:20:42 +0000 (UTC) Received: from localhost (ovpn-8-21.pek2.redhat.com [10.72.8.21]) by smtp.corp.redhat.com (Postfix) with ESMTP id 933C92166B26; Mon, 11 Jul 2022 02:20:40 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, io-uring@vger.kernel.org, Gabriel Krisman Bertazi , ZiyangZhang , Xiaoguang Wang , Ming Lei Subject: [PATCH V4 2/2] ublk_drv: add UBLK_IO_REFETCH_REQ for supporting to build as module Date: Mon, 11 Jul 2022 10:20:24 +0800 Message-Id: <20220711022024.217163-3-ming.lei@redhat.com> In-Reply-To: <20220711022024.217163-1-ming.lei@redhat.com> References: <20220711022024.217163-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Add UBLK_IO_REFETCH_REQ command to fetch the incoming io request in ubq daemon context, so we can avoid to call task_work_add(), then it is fine to build ublk driver as module. In this way, iops is affected a bit, but just by ~5% on ublk/null, given io_uring provides pretty good batching issuing & completing. One thing to be careful is race between ->queue_rq() and handling abort, which is avoided by quiescing queue when aborting queue. Except for that, handling abort becomes much easier with UBLK_IO_REFETCH_REQ since aborting handler is strictly exclusive with anything done in ubq daemon kernel context. Signed-off-by: Ming Lei --- drivers/block/Kconfig | 2 +- drivers/block/ublk_drv.c | 121 ++++++++++++++++++++++++++-------- include/uapi/linux/ublk_cmd.h | 17 +++++ 3 files changed, 113 insertions(+), 27 deletions(-) diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index d218089cdbec..2ba77fd960c2 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -409,7 +409,7 @@ config BLK_DEV_RBD If unsure, say N. config BLK_DEV_UBLK - bool "Userspace block driver" + tristate "Userspace block driver" select IO_URING help io uring based userspace block driver. diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 0076418e6fad..98482f8d1a77 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -92,6 +92,7 @@ struct ublk_queue { int q_id; int q_depth; + unsigned long flags; struct task_struct *ubq_daemon; char *io_cmd_buf; @@ -141,6 +142,15 @@ struct ublk_device { struct work_struct stop_work; }; +#define ublk_use_task_work(ubq) \ +({ \ + bool ret = false; \ + if (IS_BUILTIN(CONFIG_BLK_DEV_UBLK) && \ + !((ubq)->flags & UBLK_F_NEED_REFETCH)) \ + ret = true; \ + ret; \ +}) + static dev_t ublk_chr_devt; static struct class *ublk_chr_class; @@ -429,6 +439,26 @@ static int ublk_setup_iod(struct ublk_queue *ubq, struct request *req) return BLK_STS_OK; } +static bool ubq_daemon_is_dying(struct ublk_queue *ubq) +{ + return ubq->ubq_daemon->flags & PF_EXITING; +} + +static void ubq_complete_io_cmd(struct ublk_io *io, int res) +{ + /* mark this cmd owned by ublksrv */ + io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV; + + /* + * clear ACTIVE since we are done with this sqe/cmd slot + * We can only accept io cmd in case of being not active. + */ + io->flags &= ~UBLK_IO_FLAG_ACTIVE; + + /* tell ublksrv one io request is coming */ + io_uring_cmd_done(io->cmd, res, 0); +} + static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx, const struct blk_mq_queue_data *bd) { @@ -456,30 +486,38 @@ static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx, * If we can't add the task work, something must be wrong, schedule * monitor work immediately. */ - if (task_work_add(ubq->ubq_daemon, &data->work, notify_mode)) { - struct ublk_device *ub = rq->q->queuedata; + if (ublk_use_task_work(ubq)) { + if (task_work_add(ubq->ubq_daemon, &data->work, notify_mode)) { + struct ublk_device *ub = rq->q->queuedata; - mod_delayed_work(system_wq, &ub->monitor_work, 0); - return BLK_STS_IOERR; + mod_delayed_work(system_wq, &ub->monitor_work, 0); + return BLK_STS_IOERR; + } + } else { + if (ubq_daemon_is_dying(ubq)) { + struct ublk_device *ub = rq->q->queuedata; + + mod_delayed_work(system_wq, &ub->monitor_work, 0); + return BLK_STS_IOERR; + } + + ubq_complete_io_cmd(&ubq->ios[rq->tag], UBLK_IO_RES_REFETCH); } return BLK_STS_OK; } -static bool ubq_daemon_is_dying(struct ublk_queue *ubq) -{ - return ubq->ubq_daemon->flags & PF_EXITING; -} - static void ublk_commit_rqs(struct blk_mq_hw_ctx *hctx) { struct ublk_queue *ubq = hctx->driver_data; - __set_notify_signal(ubq->ubq_daemon); - if (ubq_daemon_is_dying(ubq)) { - struct ublk_device *ub = hctx->queue->queuedata; + if (ublk_use_task_work(ubq)) { + __set_notify_signal(ubq->ubq_daemon); + if (ubq_daemon_is_dying(ubq)) { + struct ublk_device *ub = hctx->queue->queuedata; - mod_delayed_work(system_wq, &ub->monitor_work, 0); + mod_delayed_work(system_wq, &ub->monitor_work, 0); + } } } @@ -604,17 +642,7 @@ static void ublk_rq_task_work_fn(struct callback_head *work) return; } - /* mark this cmd owned by ublksrv */ - io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV; - - /* - * clear ACTIVE since we are done with this sqe/cmd slot - * We can only accept io cmd in case of being not active. - */ - io->flags &= ~UBLK_IO_FLAG_ACTIVE; - - /* tell ublksrv one io request is coming */ - io_uring_cmd_done(io->cmd, ret, 0); + ubq_complete_io_cmd(io, ret); /* * in case task is exiting, our partner has gone, so schedule monitor @@ -737,13 +765,26 @@ static void ublk_commit_completion(struct ublk_device *ub, * Focus on aborting any in-flight request scheduled to run via task work */ static void __ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq) + __releases(&ubq->abort_lock) { bool task_exiting = !!(ubq->ubq_daemon->flags & PF_EXITING); int i; + bool quiesced = false; if (!task_exiting) goto out; + /* + * quiesce queue so that we can avoid to race with ublk_queue_rq() + * wrt. dealing with io flags + */ + if (ubq->flags & UBLK_F_NEED_REFETCH) { + spin_unlock(&ubq->abort_lock); + blk_mq_quiesce_queue(ub->ub_queue); + spin_lock(&ubq->abort_lock); + quiesced = true; + } + for (i = 0; i < ubq->q_depth; i++) { struct ublk_io *io = &ubq->ios[i]; @@ -759,6 +800,8 @@ static void __ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq) __ublk_fail_req(io, rq); } } + if (quiesced) + blk_mq_unquiesce_queue(ub->ub_queue); out: ubq->abort_work_pending = false; ublk_put_device(ub); @@ -792,8 +835,12 @@ static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq) if (!ubq->abort_work_pending) { ubq->abort_work_pending = true; put_dev = false; - if (task_work_add(ubq->ubq_daemon, &ubq->abort_work, - TWA_SIGNAL)) { + if (ublk_use_task_work(ubq)) { + if (task_work_add(ubq->ubq_daemon, + &ubq->abort_work, TWA_SIGNAL)) { + __ublk_abort_queue(ub, ubq); + } + } else { __ublk_abort_queue(ub, ubq); } } else { @@ -872,6 +919,16 @@ static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq) mutex_unlock(&ub->mutex); } +static void ublk_handle_refetch(struct ublk_device *ub, + struct ublk_queue *ubq, int tag) +{ + struct request *req = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], + tag); + struct ublk_rq_data *data = blk_mq_rq_to_pdu(req); + + ublk_rq_task_work_fn(&data->work); +} + static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) { struct ublksrv_io_cmd *ub_cmd = (struct ublksrv_io_cmd *)cmd->cmd; @@ -943,6 +1000,15 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) io->cmd = cmd; ublk_commit_completion(ub, ub_cmd); break; + case UBLK_IO_REFETCH_REQ: + if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)) + goto out; + io->addr = ub_cmd->addr; + io->cmd = cmd; + io->flags |= UBLK_IO_FLAG_ACTIVE; + io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV; + ublk_handle_refetch(ub, ubq, tag); + break; default: goto out; } @@ -983,6 +1049,7 @@ static int ublk_init_queue(struct ublk_device *ub, int q_id) void *ptr; int size; + ubq->flags = ub->dev_info.flags[0]; ubq->q_id = q_id; ubq->q_depth = ub->dev_info.queue_depth; size = ublk_queue_cmd_buf_size(ub, q_id); @@ -1381,6 +1448,8 @@ static int ublk_ctrl_add_dev(const struct ublksrv_ctrl_dev_info *info, /* update device id */ ub->dev_info.dev_id = ub->ub_number; + if (IS_MODULE(CONFIG_BLK_DEV_UBLK)) + ub->dev_info.flags[0] |= UBLK_F_NEED_REFETCH; ret = ublk_add_dev(ub); if (!ret) { diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h index 4f0c16ec875e..fe4a2c7c8349 100644 --- a/include/uapi/linux/ublk_cmd.h +++ b/include/uapi/linux/ublk_cmd.h @@ -28,12 +28,19 @@ * this IO request, request's handling result is committed to ublk * driver, meantime FETCH_REQ is piggyback, and FETCH_REQ has to be * handled before completing io request. + * + * REFETCH_REQ: issued via sqe(URING_CMD) after ublk driver returns + * UBLK_IO_REFETCH_REQ, which only purpose is to fetch io request data + * from the userspace ublk server context in case that task_work_add + * isn't available because ublk driver is built as module */ #define UBLK_IO_FETCH_REQ 0x20 #define UBLK_IO_COMMIT_AND_FETCH_REQ 0x21 +#define UBLK_IO_REFETCH_REQ 0x22 /* only ABORT means that no re-fetch */ #define UBLK_IO_RES_OK 0 +#define UBLK_IO_RES_REFETCH 1 #define UBLK_IO_RES_ABORT (-ENODEV) #define UBLKSRV_CMD_BUF_OFFSET 0 @@ -48,6 +55,16 @@ */ #define UBLK_F_SUPPORT_ZERO_COPY (1UL << 0) +/* + * When NEED_REFETCH is set, ublksrv has to issue UBLK_IO_REFETCH_REQ + * command after ublk driver returns UBLK_IO_REFETCH_REQ. + * + * This flag is negotiated during handling UBLK_CMD_ADD_DEV. If ublksrv + * sets it, ublk driver can't clear it. But if ublk driver sets it back + * to ublksrv, ublksrv has to handle it correctly. + */ +#define UBLK_F_NEED_REFETCH (1UL << 1) + /* device state */ #define UBLK_S_DEV_DEAD 0 #define UBLK_S_DEV_LIVE 1 -- 2.31.1